title: Identification of new pillared-layered carbon nitride materials at high pressure.
abstract: The compression of the layered carbon nitride C6N9H3 · HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl(-) ions contained within C12N12 voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl(-) ions out of the planes beginning above 10-20 GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer bonded phase. The transition pressure is calculated to be 47 GPa for the ideal structures. The new material has mixed sp(2)-sp(3) hybridization among the C and N atoms and it provides the first example of a pillared-layered carbon nitride material that combines the functional properties of the graphitic-like form with improved mechanical strength. Similar behavior is predicted to occur for Cl-free structures at lower pressures.
authors.affiliation: Lyman Laboratory of Physics, Harvard University, Cambridge, MA 02138, USA. salamat@physics.harvard.edu
authors.forename: Ashkan
authors.initials: A
authors.lastname: Salamat
authors.forename: Malek
authors.initials: M
authors.lastname: Deifallah
authors.forename: Raul Quesada
authors.initials: RQ
authors.lastname: Cabrera
authors.forename: Furio
authors.initials: F
authors.lastname: Corà
authors.forename: Paul F
authors.initials: PF
authors.lastname: McMillan